Unless otherwise indicated herein, the materials described in this section are not prior art to the claims and are not admitted to be prior art by inclusion in this section.
Optical communication uses light as a transmission medium to carry information from a source to a destination. In particular, the light forms an electromagnetic carrier wave that is modulated to carry the information. To transmit data, an optical communication system generally includes a transmitter, a channel, and a receiver. The transmitter encodes the data into an optical signal, the channel carries the optical signal to the receiver, and the receiver decodes to reproduce the data from the received optical signal.
Conventionally, the data is encoded into the optical signal by switching a laser on and off to transmit a series of light pulses. The occurrence of the light pulse within a given transmission time interval (TTI) represents a “1” binary value and the absence of the light with a given TTI represents a “0” binary value. Accordingly, using such conventional techniques, a single bit of data is communicated during each TTI. As a result, the maximum rate at which such data can be transmitted, received, and processed is generally limited by the speed at which the transmitter can switch on and off and/or the speed at which the receiver can detect transitions between a “1” and a “0” in the received light pulses.